1. Field of the Invention
The present invention relates to an improvement of a lock for an automatic vending machine.
2. Related Art
Recently automatic vending machines of the type which permits the use of bills or bank notes have been popularly placed and used in the street. Such automatic vending machines are very convenient for customers. Because of a lot of money stored in automatic vending machines, however, there is an increasing tendency of inducing the crime of stealing the money in these vending machines. In almost all cases criminals use iron bars and other destructive tools to open the doors of the vending machines by force. In an attempt to prevent such crimes, strong locks as shown in FIGS. 15 and 16 have been proposed and actually used.
FIG. 15 shows such a strong lock A' for vending machines as comprising cylindrical lock 4' fixed to the door m.sub.2 ' of a vending machine and having a slide plate 18'.
The slide plate 18' is responsive to rotation of the cylinder of the cylindrical lock 4' for moving longitudinally until the slide plate 18 ' has been caught by upper and lower catch pieces 19', which are fixed to the casing body m.sub.1 '. Thus, the door m.sub.2 ' of the vending machine is closed and locked to the casing body m.sub.1 ' of the vending machine at its upper and lower levels. This type of lock using a slide plate latch, however, has clamping force insufficient to prevent the door from being opened by force.
FIG. 16 shows another strong lock A' for vending machines as comprising a nut or female member 1' fixed to the casing body m.sub.1 ' of a vending machine and a rotatable bold or male member 5' fixed to the door m.sub.2 ' of the vending machine. After closing the door m.sub.2 ', the rotatable bolt 5' is rotated and driven into the nut 1' until the door is firmly locked to the casing of the vending machine at its intermediate level. This bolt-and-nut type of lock has sufficient clamping force, but the door can be opened by inserting an iron bar into the gap between the door and the casing body of the vending machine at its upper and lower levels and by tearing up the door from the casing body of the vending machine.